When the memory capacity or performance of a storage system becomes insufficient, for example, a scale-out architecture is applied to the storage system. For example, a device enclosure (DE) including a plurality of hard disks and a controller enclosure (CE) are added to the storage system. The CE includes a plurality of controller modules (CMs). Each of the CMs is connected to the hard disks. When a host device requests access to one of the hard disks, a corresponding CM controls the access to the hard disk.
Among the storage systems, there is a scale-out-type storage system to which a storage device is easily added. In this scale-out-type storage system, for example, an individual service controller (SVC) provided in a device called a front end controller (FE) manages CMs. For example, each of the CMs is connected to an SVC via a management bus. The SVC communicates with each of the CMs via a management bus, so as to manage operations of the CMs. For example, the SVC controls power supplies of the CMs, monitors statuses of the CMs, and acquires logs from the CMs. In addition, the SVC performs reset control and turns on and off light emitting diodes (LED), for example.
Various techniques are used to manage a storage system. For example, there is a system that is configured to maintain consistency of file management information. In this system, a master secondary storage control device per file is selected and determined from a plurality of secondary storage control devices by using a random number and a modulo operation. There is also a system that promptly performs accurate failure recovery when a control device or a memory in a disk storage system malfunctions. In this system, the failure recovery is performed by using mirror-type memories that synchronize with each other in real time in two control devices.
See, for example, Japanese Laid-open Patent Publication Nos. 07-244642 and 08-241173.
In a conventional scale-out-type storage system, an SVC manages CMs. Thus, when this SVC malfunctions, the system cannot be operated properly. Thus, to improve reliability, two SVCs are included in an FE. If there are two SVCs, even when one of the SVCs malfunctions, the other SVC can properly manage the CMs. However, if two SVCs are used, the size of the FE is increased. As a result, more space is needed to install the FE, and the cost is also increased.
One possible solution to this problem is to eliminate the SVCs and allow one of the plurality of CMs to manage all the CMs. If one of the CMs is allowed to manage all the CMs, no SVCs are needed in a scale-out-type storage system. Consequently, less space is needed for the installation of the system. However, even when each of the CMs is provided with the same management function as that of an SVC, it has conventionally been impossible to determine which one of the plurality of CMs needs to be the management CM. Thus, it is difficult to eliminate the SVCs and allow one of the plurality of CMs to manage all the CMs.
Each of the CMs in the above description is an example of a control device that controls storage devices. Regarding general control devices, as is the case with the CMs, it is impossible to determine which one of a plurality of control devices needs to be allowed to manage all the control devices.